Die Grundlagen der Einsteinschen Relativitäts-Theorie

Die Grundlagen der Einsteinschen Relativitäts-Theorie (English: The Fundamentals of the Einsteinian Relativity Theory) is a 1922 German partly animated documentary film created with the goal of bringing Einstein's theory of relativity to the broad public. It premiered on 2 April 1922 at the Frankfurt Fair.

With more than 80,000 individual images, it is not only the first great science film, it is also the film with the longest trick sequences.

The original version of the film is lost. As part of the research carried out by the 3sat station, an English copy of the film was filmed in 2005 with the British Film Institute, which was provided with English and English language interludes and "speech bubbles". A companion to the English version is also available.

Part of the film was used to create Max Fleischer's The Einstein Theory of Relativity.